Differential thermal analyses of solid-solid transitions in AgNO3 under hydrostatic pressures to 0.7 Gpa

1981 ◽  
Vol 34 (9) ◽  
pp. 1845 ◽  
Author(s):  
LH Cohen ◽  
Jr W Klement
Keyword(s):  
High Temperature ◽  
Growth Rates ◽  
Linear Growth ◽  
Thermal Analyses ◽  
Quantitative Description ◽  
Initial Slope ◽  
Transition Temperatures ◽  
Cooling Rates ◽  
Zero Rate ◽  
Show Temperature Dependence

Differential thermal analyses have located the transitions between low-temperature I and high-temperature II phases in AgNO3 powder and single crystals under hydrostatic pressures </~0.7 GPa, with heating/cooling rates in the range 0.1-1.5 K s-1. Isobaric transition temperatures plot linearly against heating/cooling rates and, extrapolated to zero rate, show hystereses between I → II and II → I transition temperatures which are comparable with the 'regions of indifference' of Bridgman's isothermal experiments. The present results suggest an initial slope of -0.090 μK Pa-1 and zero initial curvature for the I-II phase boundary. Greater hystereses are observed for the I-II transitions near intersection with the II-II' λ transition at </~0.7 GPa. An improved, quantitative description is achieved for the Kennedy-Schultz data on the linear growth rates of II,II? → I at 0.1 MPa. For II' (with ordered NO3- ions) → I the growth rates show temperature dependence markedly different than growth rates for II(with disordered NO3-) → 1 and I → II.

scholarly journals Studies of Formation Mechanism, Structure, and Properties of Network Copolymers Obtained by Cocuring of Rolivsan Thermosetting Resins with Aromatic Diamines

2019 ◽  
Vol 2019 ◽  
pp. 1-15
Author(s):  
B. A. Zaitsev ◽  
L. G. Kleptsova ◽  
I. D. Shvabskaya
Keyword(s):  
Glass Transition ◽  
High Temperature ◽  
Thermal Analyses ◽  
Polymer Network ◽  
Three Dimensional ◽  
Transition Temperatures ◽  
Structure And Properties ◽  
Aromatic Diamines ◽  
Thermosetting Resins ◽  
Glass Transition Temperatures

Rolivsan thermosetting resins (ROLs) demonstrate high glass-transition temperatures and excellent processability. In our work, high-temperature properties of ROLs were significantly improved using a novel technique for structural and chemical modification of microheterogeneous network polymers. This technique involves, among other procedures, cocuring of rolivsan resins with aromatic diamines (ADA). The most noticeable increase in storage moduli and glass transition temperatures (Tg) of these copolymers was achieved when ROLs were modified with 10-15 wt.% of ADA and the resulting blends were subjected to thermal treatment in air in the temperature range 180 to 320°C for several hours. FTIR, 13С NMR spectroscopy, and dynamic mechanical and thermal analyses were used for studying the structure and properties of the obtained products. It was demonstrated that the mechanism of formation of ROL-ADA copolymers includes the following high-temperature reactions: (i) three-dimensional radical copolymerization of unsaturated ROL components and (ii) cleavage of heat-sensitive methacrylate crosslinking units inside the polymer network. The second process is accompanied by formation of pending units of methacrylic acid and methacrylic anhydride, which participate in condensation reactions with ADA.

Design and Evaluation of the Fresnel-Lens Based Solar Concentrator System Through a Statistical-Algorithmic Approach

2018 ◽  
Author(s):  
Hassan Qandil ◽  
Weihuan Zhao
Keyword(s):  
High Temperature ◽  
High Efficiency ◽  
Incident Light ◽  
Thermal Analyses ◽  
Solar Spectrum ◽  
Chromatic Aberration ◽  
Fresnel Lens ◽  
Optimum Number ◽  
Solar Concentrator ◽  
Receiver System

A novel non-imaging Fresnel-lens-based solar concentrator-receiver system has been investigated to achieve high-efficiency photon and heat outputs with minimized effect of chromatic aberrations. Two types of non-imaging Fresnel lenses, a spot-flat lens and a dome-shaped lens, are designed through a statistical algorithm incorporated in MATLAB. The algorithm optimizes the lens design via a statistical ray-tracing methodology of the incident light, considering the chromatic aberration of solar spectrum, the lens-receiver spacing and aperture sizes, and the optimum number of prism grooves. An equal-groove-width of the Poly-methyl-methacrylate (PMMA) prisms is adopted in the model. The main target is to maximize ray intensity on the receiver’s aperture, and therefore, achieve the highest possible heat flux and output concentration temperature. The algorithm outputs prism and system geometries of the Fresnel-lens concentrator. The lenses coupled with solar receivers are simulated by COMSOL Multiphysics. It combines both optical and thermal analyses for the lens and receiver to study the optimum lens structure for high solar flux output. The optimized solar concentrator-receiver system can be applied to various devices which require high temperature inputs, such as concentrated photovoltaics (CPV), high-temperature stirling engine, etc.

scholarly journals Features of tin-bath hardening for small parts

2019 ◽  
Vol 27 (2) ◽  
pp. 51-54 ◽  
Author(s):  
E. S. Skorbyaschensky ◽  
V. F. Bashev ◽  
A. N. Polishko ◽  
S. N. Antropov
Keyword(s):  
High Temperature ◽  
Martensitic Transformation ◽  
Specific Surface ◽  
Phase Ratio ◽  
Cooling Curves ◽  
Cooling Rates ◽  
Practical Possibility ◽  
Low Weight ◽  
Temperature Ranges ◽  
Small Parts

The method of quenching in tin melt was tested for low-weight parts with a large specific surface, made of a number of steels with a high temperature of the onset of martensitic transformation. The advantages of this method in comparison with traditional hardening technologies are established, as well as regularities in the change of cooling curves for various mass ratios of the part and the quencher are revealed. The practical possibility of adjusting the cooling rates in the process of hardening in various temperature ranges in order to optimize the phase ratio in steel while maintaining the possibility of preventing the occurrence of microcracks is shown.

scholarly journals Steady-state radiative cooling rates for low-density, high-temperature plasmas

1977 ◽  
Vol 20 (5) ◽  
pp. 397-439 ◽  
Author(s):  
D.E. Post ◽  
R.V. Jensen ◽  
C.B. Tarter ◽  
W.H. Grasberger ◽  
W.A. Lokke
Keyword(s):  
Steady State ◽  
High Temperature ◽  
Radiative Cooling ◽  
Low Density ◽  
Cooling Rates

An Electrodeless Melter for Vitrification of Nuclear Waste

1996 ◽  
Vol 465 ◽  
Author(s):  
J. P. Freidberg ◽  
A. J. Shajii ◽  
K. W. Wenzel ◽  
J. R. Lierzer
Keyword(s):  
High Temperature ◽  
Radioactive Waste ◽  
Nuclear Waste ◽  
Thermal Analyses ◽  
Iron Core ◽  
Leaching Rate ◽  
One Dimensional ◽  
High Silica ◽  
Waste Loading

ABSTRACTThis paper describes a new concept for a high-temperature, electrodeless melter for vitrifying radioactive wastes. Based on the principles of induction heating, it circumvents a number of difficulties associated with existing technology. The melter can operate at higher temperatures (1500–2000°C vs 1150°C), allowing for a higher quality, more durable glass which reduces the long-term leaching rate. Higher processing temperatures also enable conversion from borosilicate to high-silica glass which can accommodate 2 to 3 times as much radioactive waste, potentially halving the ultimate required long-term disposal space. Finally, with high temperatures, conversion of nuclear waste into ceramics can also be considered. This too leads to higher waste loading and the reduction of repository space. The melter is toroidal, linked by an iron core transformer that allows efficient electrical operation even at 60 Hz. One-dimensional electrical and thermal analyses are presented.

COMPARATIVE STUDIES OF NORTH AMERICAN AND EUROPEAN CULTURES OF THE ROOT ROT FUNGUS, FOMES ANNOSUS (FR.) COOKE

1955 ◽  
Vol 33 (5) ◽  
pp. 416-428 ◽  
Author(s):  
D. E. Etheridge
Keyword(s):  
Growth Rate ◽  
North American ◽  
Growth Rates ◽  
Root Rot ◽  
Linear Growth ◽  
Morphological Characteristics ◽  
Dry Weight ◽  
Cellulolytic Activity ◽  
Ph Optimum ◽  
Two Cultures

Cultures of Fames annosus originating in Europe could not be distinguished from those originating in North America either by colony appearance, growth rate, pH optimum, or cellulolytic activity. Three growth rate types on 2.5% malt agar were recognized and these are ascribed to individual variation rather than to host or geographical influences. Successive subculturing produced variants that fell into three growth classes. Half of the isolates displayed spontaneous, but reversible, changes in growth rate and colony appearance during subculturing and this is discussed from the standpoint of genetical and environmental influences. Cultures displaying different morphological characteristics and linear-growth rates differed little metabolically; each had a similar pH optimum ranging from 4.6 to 5.5, and each proved capable of altering the initial acidity of the medium to a reaction which was more suitable for growth. Two cultures were characterized by double pH optima at 4.6 and 5.5. Cultures having different linear-growth rates produced about the same dry-weight of mycelium on a cellulose substrate in a semisynthetic nutrient solution. On the basis of a statistical analysis of cellulose utilization by representative isolates it was impossible to distinguish between North American and European cultures.

Abstract 13513: Serial CT Surveillance of Abdominal Aortic Aneurysm Diameter Demonstrates Predominantly Linear Growth (N-TA 3 CT)

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Sydney Olson ◽  
Marniker Wijesinha ◽  
Annalise Panthofer ◽  
William Blackwelder ◽  
Gilbert R Upchurch ◽  
...  
Keyword(s):  
Growth Rate ◽  
Growth Rates ◽  
Linear Growth ◽  
Growth Patterns ◽  
Aortic Aneurysms ◽  
Transverse Diameter ◽  
Invasive Treatment ◽  
Abdominal Aortic ◽  
Risk Of Rupture ◽  
Serial Ct

Objective: Small abdominal aortic aneurysms (AAAs) have a low risk of rupture. Intervention is indicated when diameters exceed established thresholds. This study assessed the growth rates and patterns of AAAs over 2 years as documented on serial CT scans from the Non-Invasive Treatment of AAA Clinical Trial. Methods: 254 patients, 35 females with baseline AAA maximum transverse diameter (MTD) between 3.5-4.5 cm and 219 males with baseline MTD 3.5-5.0 cm, were included in this study. Linear regressions and segmental growth rates were used to model growth rates and patterns. Results: The yearly growth rates of AAA MTDs had a median of 0.17 cm/yr and mean of 0.19 cm/yr ± 0.14 (Figure 1). 10% of AAA displayed minimal to no growth (< 0.05 cm/yr), 62% low growth (0.05-0.25 cm/yr), 28% high growth (> 0.25 cm/yr). Baseline AAA diameter accounted for only 5.4% of growth rate variance (P<0.001, R 2 0.05). Most AAAs displayed linear growth (70%); large variations in interval growth rates occurred infrequently (3% staccato growth, 4% exponential growth); a minority of subjects’ growth patterns were not clearly classifiable (11% indeterminate-not growing, 12% indeterminate-growing) (Figure 2). No patients with baseline MTD < 4.25 cm exceeded sex-specific repair thresholds (males 0 / 92, [95% CI, 0.00-0.06]; females 0 / 25 [95% CI, 0.00-0.25]) in the course of follow-up for as long as two years. Conclusions: The majority of small AAAs exhibit linear growth; large intra-patient growth rate variations were infrequently observed over 2 years. AAA < 4.25 cm can be followed with a CT scan in 2 years with little chance of exceeding interventional MTD thresholds of 5.5 cm for men.

High-Temperature Modifications of Thorium Dicarbide

1964 ◽  
Vol 8 ◽  
pp. 78-85 ◽  
Author(s):  
P. K. Gantzel ◽  
S. Langer ◽  
N. L. Baldwin ◽  
F. L. Kester
Keyword(s):  
Thermal Analysis ◽  
Differential Thermal Analysis ◽  
High Temperature ◽  
Thermal Effects ◽  
Room Temperature ◽  
Thermal Analyses ◽  
Tetragonal Modification ◽  
X Ray ◽  
Space Groups ◽  
Heating And Cooling

AbstractThermal analyses of samples of thorium dicarbide in equilibrium with graphite show arrests which indicate phase transitions at 1427 ± 21°C arid 1481 ± 28°C. These thermal effects have been observed on heating and cooling both in standard thermal analysis and in differential thermal analysis using graphite as a reference material. The microstructure of thorium dicarbide samples shows the characteristic “herringbone” pattern of a material which has undergone a martensitic-type transition.A high-temperature X-ray investigation has revealed that the observed thermal arrests correspond to erystallographic transformations. The monodinic modification found at room temperature is stable to 1427°C, at which temperature a tetragonal modification with a0 = 4.235 ± 0.002Å and c0 = 5.408 ± 0.002Å is formed. At 1481°C, the tetragonal is transformed to cubic with a0 = 5.809 ± 0.002 Å. The best agreement between observed and calculated intensities has been obtained with C-C units of 1.5-Å assumed bond length in space groups P42/mmc and Pa3 for the tetragonal and cubic modifications, respectively.

Effects of growth rates and cooling rates on defect generation in melt-grown copper crystals

1974 ◽  
Vol 24-25 ◽  
pp. 418-421 ◽  
Author(s):  
Tetsuo Inoue ◽  
Jirô Watanabé ◽  
Mikio Yamamoto
Keyword(s):  
Growth Rates ◽  
Cooling Rates ◽  
Defect Generation ◽  
Copper Crystals
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